The present invention relates to a paper feeding device for drawing a blank paper from a paper roll and feeding it to a printer or the like.
Paper roll is frequently used as the source of recording paper in a printer and in a facsimile equipment.
Usually, a paper roll is used continuously or used on occasion in accordance with printing input and others with no operator once set and no trouble can be found out in many cases to require maximum avoidance of trouble. However, practical handling of paper roll is very difficult and the problems such as follows may often occur in the paper feeding process of drawing a blank paper from a paper roll.
1) For example, in a process in which a paper roll is freely contactively supported on the bottom of a paper-containing box with no support for the axis thereof and the blank paper is drawn, the paper roll moves up-and-down around the contact point P on the front wall of the housing C as the fulcrum by the drawing force F for the paper roll as shown in FIG. 11 to cause fluctuation of tension F applied on the blank paper and meandering of the blank paper and thus to make drawing of the blank unstable and often to cause disorder in the printed letters.
When the blank paper is drawn by supporting the center O of the paper roll with a fixed shaft R as shown in FIG. 12, it is required to give a damping torque to establish a proper tension F when the paper roll is drawn and thus it is required to provide a mechanism for forming frictional resistance on the fixed shaft R.
As the diameter of the paper roll changes gradually during feeding, a complex mechanism is required to give proper friction, resulting in causing high equipment cost.
2) A paper roll has a curl and the part of smaller diameter has a higher curl. It is required to prevent trouble by removing the curl with any method.
To remove the curl, it is required to draw the paper with a tension corresponding the degree of curl in a condition that the paper roll is incurvated to the direction reverse to the curl. For this purpose, devices in the prior art have been so constituted that a constant brake force is applied on the shaft for supporting the paper roll to draw the paper with a tension not lower than a predetermined level. The effect for removing curl depends on the incurvation diameter and the tension applied on the paper. The curvation diameter is constant by the diameter of a curl removing roller. Hence, the effect for removing curl is determined by the tension applied on the paper.
The tension applied on the paper should be defined by the brake force of the shaft for supporting the paper roll and the brake force applied on the shaft for supporting the paper roll would be constant in a conventional brake mechanism. After all, there has been a difficulty that the curl could not be removed completely in the course of a gradually reduction in the diameter of the paper roll.
There has been also a difficulty that the device became to be too complex and thus too high price in order to adjust the brake force of the paper roll in accordance with the diameter of the paper roll.
The principal object of the present invention is to provide an economic paper feeding device which can feed unrolled paper stably.
Another object of the present invention is to provide a device which can draw stably unrolled paper from a paper feeding box and feed to the recording part by a simple constitution.
The third object of the invention is to provide a paper feeding device which can feed unrolled paper stably in a condition suitable for use by a simple equipment.
The fourth object of the present invention is to provide an economic printer equipment which can handle the blank paper stably and can be used efficiently.